/changelog groups releases under the chapter they closed #11896

/changelog now shows releases that a closed chapter shipped under a heading with the chapter's name, its meaning line and its closing note. Releases between chapters stay flat, and a changelog with no chapters renders exactly as before.

I haven't taken the 390 px and 1280 px screenshots: the sandbox has no browser and can't reach the app. The new tests, the existing changelog tests, tsc, scripts/gate.ts and scripts/design-lint.ts pass. I didn't run the full suite; the forge's check does that on the push.

• Grouping: groupLandings(landings, chapters, now) is a pure function in src/web/pages/changelog.ts. A landing belongs to a closed chapter of its repository when it merged after the chapter opened and no later than it closed.
• Chapter heading: a chapter sits at its newest release and links to its chapter page.
• Closing note: shown in a native <details> as chapter_notes.ts worded it at close; nothing is recomputed. It's server-rendered with no script.
• Not drawn: a chapter with no release yet, one still open, one closing after now, and one from a repository the reader can't see.
• Tests: test/changelog-chapters.test.ts covers two chapters plus loose releases in newest-first order, the empty chapter, the unseen repository, and escaping.
• Cache: the chapters are part of the cache and etag key, so closing one refreshes the page.
• scripts/gate.ts: it picks up test files on its own, so the new test needed no entry there.

I chose not to touch the day-regrouping script beyond one line. When chapters are shown it leaves the server's UTC day grouping alone, because moving rows between days would break the chapter order.

Release membership is decided by merge time against the chapter's opened and closed times, since a landing doesn't record the tag it shipped in. The page doesn't use Release rows. src/core/chapters.ts is only read.

To try it: close a chapter in a repository that has merged pulls, then open /changelog.

Closes #11868

/changelog now shows releases that a closed chapter shipped under a heading with the chapter's name, its meaning line and its closing note. Releases between chapters stay flat, and a changelog with no chapters renders exactly as before.

I haven't taken the 390 px and 1280 px screenshots: the sandbox has no browser and can't reach the app. The new tests, the existing changelog tests, tsc, scripts/gate.ts and scripts/design-lint.ts pass. I didn't run the full suite; the forge's check does that on the push.

• Grouping: groupLandings(landings, chapters, now) is a pure function in src/web/pages/changelog.ts. A landing belongs to a closed chapter of its repository when it merged after the chapter opened and no later than it closed.
• Chapter heading: a chapter sits at its newest release and links to its chapter page.
• Closing note: shown in a native <details> as chapter_notes.ts worded it at close; nothing is recomputed. It's server-rendered with no script.
• Not drawn: a chapter with no release yet, one still open, one closing after now, and one from a repository the reader can't see.
• Tests: test/changelog-chapters.test.ts covers two chapters plus loose releases in newest-first order, the empty chapter, the unseen repository, and escaping.
• Cache: the chapters are part of the cache and etag key, so closing one refreshes the page.
• scripts/gate.ts: it picks up test files on its own, so the new test needed no entry there.

I chose not to touch the day-regrouping script beyond one line. When chapters are shown it leaves the server's UTC day grouping alone, because moving rows between days would break the chapter order.

Release membership is decided by merge time against the chapter's opened and closed times, since a landing doesn't record the tag it shipped in. The page doesn't use Release rows. src/core/chapters.ts is only read.

To try it: close a chapter in a repository that has merged pulls, then open /changelog.

/changelog now groups pulls under the chapter they closed, and the terminal's Changelog screen groups releases the same way. Screenshots at 390 px and 1280 px are not provided, because I can't take them from this sandbox. The tests that cover the change pass: bun x tsc --noEmit, bun scripts/gate.ts, bun scripts/design-lint.ts, and 130 tests across 15 changelog and TUI files. bun scripts/fast.ts named about 1,970 files, so I ran the changelog and TUI tests by hand and did not run the full suite.

What changed

• Terminal: changelogLines in src/tui/screens/changelog.ts draws a Chapter v1 line over the indented releases that fell in that chapter's window. The line shows the release count and the note's first sentence. Enter on a chapter line does nothing.
• Shared rules: src/release/chapter_words.ts holds the membership test and noteWords, so the page and terminal can't disagree.
• Page markup: the hand-rolled <h2> with a count badge is gone. A chapter is one row() with the name linked to its page, the note as meta, "Means" and "Pulls" as the facts dl, and the close date as the trail. No new class; docs/design/areas/changelog.md records this.
• Closing note: noteWords strips headings, emphasis, code marks, links and HTML and keeps the first sentence, up to 200 characters. The <details><pre> is gone.
• Dates: a chapter's pulls sit under the usual day headings, so each row keeps its date. The browser's day regrouping still skips pages with chapters.
• Queries per request: the page's ETag now holds one aggregate query, chapterStamp (closed-chapter count, newest close, per-repository visibility). The per-repository chapterEntries reads run only after the tag misses, so a 304 costs one query.
• Docs: docs/features/changelog.md has a "Chapters" paragraph, including the time-window caveat below.

Tests added (in test/changelog-chapters.test.ts and test/tui-changelog.test.ts)

• A real private repo with a closed chapter: its owner gets the chapter, and an outsider and an anonymous reader get none, both from groupLandings and in the rendered region.
• noteWords, including its length cap.
• chapterStamp changes when a chapter closes.
• Day headings inside a chapter.
• The terminal grouping.

Not done

• No screenshots, and the preview was not checked. The preview's seed has no closed chapter, which is why /changelog draws none there.
• Membership is still by merge-time window. I chose not to record the tag per landing; the docs say a landing at a window's edge can be placed in a neighbouring chapter.
• The stamp doesn't catch a change in org access to a private repository. The ETag covers user id, admin flag and repository visibility; a reader whose access changes mid-cache could briefly get a 304. Say if you want per-repository canRead in the key; that brings back a per-repository cost on the 304 path.

Left #11868 open: 1 unticked item remain (Screenshots of /changelog at 390 px and 1280 px.).